pH- and time-dependent hemoglobin transitions: a case study for process modelling

A Novel Molecular Approach for Enhancing the Safety of Ozone in Autohemotherapy and Insights into Heme Pocket Autoxidation of Hemoglobin

Major ozone autohemotherapy (MAH) is a popular clinical practice for treating a variety of pathological conditions due to the mild and controlled oxidative stress produced by the reaction of ozone gas with other biological components. Previous studies have shown that blood ozonation leads to structural changes in hemoglobin (Hb); therefore, in the present study, the molecular effects of ozonation on Hb of a healthy individual were assessed by ozonating whole blood samples with single doses of ozone at 40, 60, and 80 μg/mL or double doses of ozone at 20 + 20, 30 + 30, and 40 + 40 μg/mL ozone to investigate whether ozonating once versus twice (but with the same final ozone concentration) would have varying effects on Hb. Additionally, our study aimed to verify whether using a very high ozone concentration (80 + 80 μg/mL), despite mixing it with blood in two steps, would result in Hb autoxidation. The pH, oxygen partial pressure, and saturation percentage of the whole blood samples were measured through a venous blood gas test, and the purified Hb samples were analyzed using several techniques including intrinsic fluorescence, circular dichroism and UV-vis absorption spectroscopies, SDS-polyacrylamide gel electrophoresis, dynamic light scattering, and a zeta potential analyzer. Structural and sequence analyses were also used to study the Hb heme pocket autoxidation sites and the residues involved. The results showed that the oligomerization and instability of Hb can be reduced if the ozone concentration to be used in MAH is divided into two doses. Indeed, our study demonstrated that two-step ozonation with 20, 30, and 40 μg/mL of ozone instead of single-dose ozonation with 40, 60, and 80 μg/mL of ozone reduced the potential adverse effects of ozone on Hb including protein instability and oligomerization. Moreover, it was found that for certain residues, their orientation or displacement leads to the entry of excess water molecules into the heme moiety, which can contribute to Hb autoxidation. Additionally, the autoxidation rate was found to be higher in alpha globins compared to beta globins.

Highlighting the Importance of Water Alkalinity Using Phosphate Buffer Diluted With Deionized, Double Distilled and Tap Water, in Lowering Oxidation Effects on Human Hemoglobin Ozonated at High Ozone Concentrations in vitro

In autohemotherapy, it is important to find a way to lower the effects of oxidation, especially at high concentrations of ozone. One of the parameters, other than ozone concentration, which can have a significant effect on the stability and rate of decomposition of ozone at high concentrations, is the presence of ions in water. A number of spectroscopic techniques including intrinsic fluorescence, circular dichroism and UV–VIS were used as well as SDS-PAGE, Native-PAGE dynamic light scattering and water ion analysis, in order to investigate the effects of two relatively high concentrations of ozone on purified human hemoglobin (Hb) in phosphate buffer and diluted versions with deionized, double distilled and tap water in vitro. Purified human Hb and not whole blood human Hb was used in this study, since the addition of water to the whole blood would have caused the RBCs to lyse, affecting the purification of Hb for further analysis. Therefore, using purified Hb, it was possible to investigate the effects of dilution of 50 mM phosphate buffer to 10 mM phosphate buffer with different water types including non-ion containing deionized and double distilled water as well as ion-containing tap water, when ozonated at 55 and 80 μg/ml ozone. The fundamental changes in the secondary and tertiary structures of Hb were seen to be related to non-ozonated Hb samples diluted with deionized and double distilled waters, respectively. Generally, Hb oligomerization was more likely to occur at the higher concentration of ozone (80 μg/ml) and in samples where phosphate buffer was diluted with non-ion containing deionized and double distilled waters and not the ion-containing tap water. This could be explained by the presence of water alkalinity or bicarbonate ions in tap water, which can scavenge free radicals and reduce Hb oxidation/oligomerization. Therefore, it was concluded that Hb could best withstand high concentrations of ozone in the presence of the undiluted 50 mM phosphate buffer followed by phosphate buffer diluted with tap water, containing bicarbonate ions.

Direct Mechanistic Evidence for a Nonheme Complex Reaction through a Multivariate XAS Analysis

In this work, we propose a method to directly determine the mechanism of the reaction between the nonheme complex Fe^II(tris(2-pyridylmethyl)amine) ([Fe^II(TPA)(CH₃CN)₂]²⁺) and peracetic acid (AcOOH) in CH₃CN, working at room temperature. A multivariate analysis is applied to the time-resolved coupled energy-dispersive X-ray absorption spectroscopy (EDXAS) reaction data, from which a set of spectral and concentration profiles for the reaction key species is derived. These “pure” extracted EDXAS spectra are then quantitatively characterized by full multiple scattering (MS) calculations. As a result, structural information for the elusive reaction intermediates [Fe^III(TPA)(κ²-OOAc)]²⁺ and [Fe^IV(TPA)(O)(X)]^+/2+ is obtained, and it is suggested that X = AcO^– in opposition to X = CH₃CN. The employed strategy is promising both for the spectroscopic characterization of reaction intermediates that are labile or silent to the conventional spectroscopic techniques, as well as for the mechanistic understanding of complex redox reactions involving organic substrates.

A combined multivariate and theoretical XAS analysis was proven to be a powerful method to obtain direct evidence for the mechanism of the reaction between the nonheme complex Fe^II(tris(2-pyridymethyl)amine) ([Fe^II(TPA)(CH₃CN)₂]²⁺) and peroxyacetic acid. This approach allowed to determine the time evolution of the concentration profiles for all reaction intermediates and to quantitatively characterize their structures, suggesting the sixth coordinating ligand of the nonheme oxo complex [Fe^IV(TPA)(O)(X)]^+/2+ is X = AcO⁻ in opposition to X = CH₃CN.

Personalizing the safe, appropriate and effective concentration(s) of ozone for a non-diabetic individual and four type II diabetic patients in autohemotherapy through blood hemoglobin analysis

Background

Diabetes is a chronic disease associated with many problems and high costs. In recent decades, a lot of research has been carried out in order to improve methods of treatment of diabetic patients. One of the currently used complementary therapies for diabetes is ozone therapy or autohemotherapy. The beneficial effects of ozone has been proven in many diseases such as diabetes, but the critical issue is the determination of the safe and effective concentration of ozone reacting with blood and in particular hemoglobin.

Methods

A number of spectroscopic techniques including intrinsic fluorescence, circular dichroism and UV–VIS spectroscopies were used as well as SDS-PAGE, Native-PAGE and dynamic light scattering to analyze the effect of ozonation on hemoglobin of a non-diabetic individual and four diabetic patients in order to find the appropriate concentration(s) of ozone for personalized autohemotherapy.

Results

In this study, we determined the personalized concentration(s) for a safe and effective ozonation of a non-diabetic individual and four diabetic type II patients, based on blood hemoglobin analysis.

Conclusions

A number of techniques were used to determine the personalized ozone concentration(s) for a safe and effective autohemotherapy based on blood hemoglobin analysis. SDS-PAGE and dynamic light scattering were identified as the two main techniques needed for personalizing the ozone concentration(s) for each individual as otherwise hemoglobin in blood can oligomerise and cause serious damage if the inappropriate ozone concentration is used.

Molecular insights into the effect of ozone on human hemoglobin in autohemotherapy: Highlighting the importance of the presence of blood antioxidants during ozonation

Ozone has been known for several decades, with its antiseptic and therapeutic effects determined by the hormesis theory. It is shown that the therapeutic efficacy of ozone therapy may be partly due to the controlled and moderate oxidative stress produced by the reaction of ozone with several biological components. In this study, the effect of ozone on healthy human hemoglobin (Hb) in the whole blood environment (in the presence of antioxidants) and in the purified form (in the absence of antioxidants) is investigated using a number of different techniques including intrinsic fluorescence, circular dichroism and UV-VIS absorption spectroscopy as well as SDS- and Native-PAGE and dynamic light scattering. The results show that the presence of antioxidants prevents damage to Hb while its absence means that as the exposure to ozone is increased, Hb is increasingly damaged. These results highlight the importance for the use of appropriate doses of ozone, for patients with different diseases and hence antioxidant levels, in autohemotherapy.

Deep eutectic-water binary solvent associations investigated by vibrational spectroscopy and chemometrics

Investigation of the behaviour of deep eutectic solvents (DESs) as novel green solvents in the presence of other solvents is of great interest. In this study the behaviour of a common natural DES, namely choline chloride-glycerol deep eutectic solvent (GDES), was studied in the presence of water. A detailed study of the association of the two solvents was performed by integration of two vibrational spectroscopic methods (FTIR and Raman spectroscopy) followed by multivariate analysis. Moreover, a binary mixture of glycerol (Gly) as one of the liquid constituents of GDES and water was explored under the same conditions. A quintuplet and ternary systems were resolved for GDES-water and Gly-water probes, respectively, using multivariate analysis of global data (multi-technique and multi-experiment data arrangements). The results confirmed that in the presence of water the GDES showed different behaviour from its components. Therefore, a DES can be introduced as an independent solvent with its unique properties. Also, different H-bond interaction energies of GDES and its pure components in the presence of water were shown by theoretical calculations based on a density functional theory framework. To investigate the effects of water on the structure of GDES, molecular dynamics (MD) simulations of GDES-water liquid mixtures were performed at 0.9 mole fraction of water.

Study of monoprotic acid-base equilibria in aqueous micellar solutions of nonionic surfactants using spectrophotometry and chemometrics

Many studies have shown the distribution of solutes between aqueous phase and micellar pseudo-phase in aqueous micellar solutions. However, spectrophotometric studies of acid-base equilibria in these media do not confirm such distribution because of the collinearity between concentrations of chemical species in the two phases. The collinearity causes the number of detected species to be equal to the number of species in a homogenous solution that automatically misinterpreted as homogeneity of micellar solutions, therefore the collinearity is often neglected. This interpretation is in contradiction to the distribution theory in micellar media that must be avoided. Acid-base equilibrium of an indicator was studied in aqueous micellar solutions of a nonionic surfactant to address the collinearity using UV/Visible spectrophotometry. Simultaneous analysis (matrix augmentation) of the equilibrium and solvation data was applied to eliminate the collinearity from the equilibrium data. A model was then suggested for the equilibrium that was fitted to the augmented data to estimate distribution coefficients of the species between the two phases. Moreover, complete resolution of concentration and spectral profiles of species in each phase was achieved.

Heme degradation upon production of endogenous hydrogen peroxide via interaction of hemoglobin with sodium dodecyl sulfate

In this study the hemoglobin heme degradation upon interaction with sodium dodecyl sulfate (SDS) was investigated using UV-vis and fluorescence spectroscopy, multivariate curve resolution analysis, and chemiluminescence method. Our results showed that heme degradation occurred during interaction of hemoglobin with SDS producing three fluorescent components. We showed that the hydrogen peroxide, produced during this interaction, caused heme degradation. In addition, the endogenous hydrogen peroxide was more effective in hemoglobin heme degradation compared to exogenously added hydrogen peroxide. The endogenous form of hydrogen peroxide altered oxyHb to aquamethemoglobin and hemichrome at low concentration. In contrast, the exogenous hydrogen peroxide lacked this ability under same conditions.

Investigation of interaction of nuclear fast red with human serum albumin by experimental and computational approaches

For the first time, interaction of nuclear fast red (NFR) with human serum albumin (HSA) was studied by experimental and computational approaches. Firstly, experimental measurements including fluorescence spectroscopy (F), UVvis spectrophotometry (UVvis), cyclic voltammetry (CV), differential pulse voltammetry (DPV) and linear sweep voltammetry (LSV) were separately used to investigate the interaction of NFR with HSA and interesting thermodynamics information was obtained from these studies. Secondly, new information including electrochemical behavior of NFR-HSA complex species, relative concentrations of the various reacting species and effects of NFR on the sub-structure of HSA was obtained by applying multivariate curve resolution-alternating least squares (MCR-ALS). In this case, a row- and column-wise augmented matrix was built with DPV, LSV, F and UVvis sub-matrices and resolved by MCR-ALS. Surprisingly, by this method two NFR-HSA complex species with different stoichiometries and different electrochemical behaviors were found. Furthermore, by the use of the recorded voltammetric and spectroscopic data the binding constants of complex species were computed by EQUISPEC (a hard-modeling algorithm). Finally, the binding of NFR to HSA was modeled by molecular modeling and molecular dynamics (MD) simulations methods. Excellent agreement was found between experimental and computational results. Both experimental and computational results suggested that the NFR binds mainly to the sub-domain IIA of HSA.

Multivariate curve resolution: a review of advanced and tailored applications and challenges

Multivariate curve resolution (MCR) is a widespread methodology for the analysis of process data in many different application fields. This article intends to propose a critical review of the recently published works. Particular attention will be paid to situations requiring advanced and tailored applications of multivariate curve resolution, dealing with improvements in preprocessing methods, multi-set data arrangements, tailored constraints, issues related to non-ideal noise structure and deviation to linearity. These analytical issues are tackling the limits of applicability of MCR methods and, therefore, they can be considered as the most challenging ones.

EPR spectroscopy of nitrite complexes of methemoglobin

The chemical interplay of nitrogen oxides (NO's) with hemoglobin (Hb) has attracted considerable recent attention because of its potential significance in the mechanism of NO-related vasoactivity regulated by Hb. An important theme of this interplay-redox coupling in adducts of heme iron and NO's-has sparked renewed interest in fundamental studies of FeNO(x) coordination complexes. In this Article, we report combined UV-vis and comprehensive electron paramagnetic resonance (EPR) spectroscopic studies that address intriguing questions raised in recent studies of the structure and affinity of the nitrite ligand in complexes with Fe(III) in methemoglobin (metHb). EPR spectra of metHb/NO(2)(-) are found to exhibit a characteristic doubling in their sharper spectral features. Comparative EPR measurements at X- and S-band frequencies, and in D(2)O versus H(2)O, argue against the assignment of this splitting as hyperfine structure. Correlated changes in the EPR spectra with pH enable complete assignment of the spectrum as deriving from the overlap of two low-spin species with g values of 3.018, 2.122, 1.45 and 2.870, 2.304, 1.45 (values for samples at 20 K and pH 7.4 in phosphate-buffered saline). These g values are typical of g values found for other heme proteins with N-coordinated ligands in the binding pocket and are thus suggestive of N-nitro versus O-nitrito coordination. The positions and shapes of the spectral lines vary only slightly with temperature until motional averaging ensues at approximately 150 K. The pattern of motional averaging in the variable-temperature EPR spectra and EPR studies of Fe(III)NO(2)(-)/Fe(II)NO hybrids suggest that one of two species is present in both of the alpha and beta subunits, while the other is exclusive to the beta subunit. Our results also reconfirm that the affinity of nitrite for metHb is of millimolar magnitude, thereby making a direct role for nitrite in physiological hypoxic vasodilation difficult to justify.

Multivariate curve resolution-alternating least squares (MCR-ALS) applied to spectroscopic data from monitoring chemical reactions processes

This paper overviews the application of multivariate curve resolution (optimized by alternating least squares) to spectroscopic data acquired by monitoring chemical reactions and other processes. The goals of the resolution methods and the principles for understanding their applications are described. Some of the problems arising from these evolving systems and the limitations of the multivariate curve resolution methods are also discussed. This article reviews most of the applications of multivariate curve resolution applied to reacting systems published between January 2000 and June 2007. Some basic papers dated before 2000 have also been included.